Crystal chemistry of selenates with mineral-like structures: VII. The structure of (H3O)[(UO2)(SeO4)(SeO2OH)] and some structural features of selenite-selenates

Krivovichev, Sergey V.

doi:10.1134/s1075701509070150

Cited by 6 publications

(6 citation statements)

References 6 publications

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“…Several compounds obtained in different ways should be mentioned separately. Compounds 22 [44] and 23 [45] were obtained during evaporation at room temperature. The first compound was obtained from the reaction of UO 2 (NO 3 ) 2 ·6H 2 O with selenic acid (H 2 SeO 4 ) in aqueous medium for 1 year, which could be explained by the reduction of Se(VI) to Se(IV) in the solution during the experiment.…”

Section: Synthetic Uranyl Compounds With Selenite Ionsmentioning

confidence: 99%

Crystal Chemistry and Structural Complexity of Natural and Synthetic Uranyl Selenites

et al. 2019

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Comparison of the natural and synthetic phases allows an overview to be made and even an understanding of the crystal growth processes and mechanisms of the particular crystal structure formation. Thus, in this work, we review the crystal chemistry of the family of uranyl selenite compounds, paying special attention to the pathways of synthesis and topological analysis of the known crystal structures. Comparison of the isotypic natural and synthetic uranyl-bearing compounds suggests that uranyl selenite mineral formation requires heating, which most likely can be attributed to the radioactive decay. Structural complexity studies revealed that the majority of synthetic compounds have the topological symmetry of uranyl selenite building blocks equal to the structural symmetry, which means that the highest symmetry of uranyl complexes is preserved regardless of the interstitial filling of the structures. Whereas the real symmetry of U-Se complexes in the structures of minerals is lower than their topological symmetry, which means that interstitial cations and H 2 O molecules significantly affect the structural architecture of natural compounds. At the same time, structural complexity parameters for the whole structure are usually higher for the minerals than those for the synthetic compounds of a similar or close organization, which probably indicates the preferred existence of such natural-born architectures. In addition, the reexamination of the crystal structures of two uranyl selenite minerals guilleminite and demesmaekerite is reported. As a result of the single crystal X-ray diffraction analysis of demesmaekerite, Pb 2 Cu 5 [(UO 2 ) 2 (SeO 3 ) 6 (OH) 6 ](H 2 O) 2 , the H atoms positions belonging to the interstitial H 2 O molecules were assigned. The refinement of the guilleminite crystal structure allowed the determination of an additional site arranged within the void of the interlayer space and occupied by an H 2 O molecule, which suggests the formula of guilleminite to be written as Ba 3 . occurrence is limited to just a few localities. First, these are Musonoi and Shinkolobwe mines in DR Congo [6], two of the minerals were only found in the Repete mine (San Juan County, Utah, USA) [5], and a few more occurrences in Europe could be mentioned (small uranium deposit Zálesí in the Czech Republic, Liauzun in France, and La Creusaz U prospect in Switzerland) [8]. Nevertheless, apart from mineralogy, uranyl selenites are of great interest from the geochemical and radiochemical points of view. It is known that fission products contain 53 g per ton [9] of long-lived 79 Se isotope with a half-life of 1.1 × 10 6 years [10] after three years of nuclear fuel irradiation in the reactor. Thus, an understanding of the processes of mineral formation in nature and their synthetic analogs in laboratories can help in the processing of nuclear wastes. Crystal chemical and structural investigations are key points in such a material's scientific studies due to the essential knowledge of how the variation in the chemical composi...

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Section: Synthetic Uranyl Compounds With Selenite Ionsmentioning

confidence: 99%

Crystal Chemistry and Structural Complexity of Natural and Synthetic Uranyl Selenites

et al. 2019

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“…The U–Se/Te 4+ –O family also shows a similar pie chart with U–P/As 3+ –O, and each structure contains HSeO 3 – trigonal pyramids and/or SeO 3 2– pseudo-tetrahedra. Only one phase (H 3 O)UO 2 (SeO 4 )(SeO 2 (OH)) involves hexavalent selenate and tetravalent selenite. Almost half of the structures for the U–Se/Te 4+ –O system have 5-coordinated uranyl, and structures of 10 phases possess mixed 4- and 5-coordinated and 5- and 6-coordinated uranyls.…”

Section: Resultsmentioning

confidence: 99%

Structural and Spectroscopic Investigation of Novel 2D and 3D Uranium Oxo-Silicates/Germanates and Some Statistical Aspects of Uranyl Coordination in Oxo-Salts

Langer

Kegler

et al. 2019

Inorg. Chem.

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Synthesis, structural and spectroscopic characterization, and topological analysis of five novel uranyl-based silicates and germanates have been performed. The open-framework K4(UO2)2Si8O20·4H2O has been synthesized under hydrothermal conditions and is based upon [USi6] heptamers interconnected via edge-sharing. Its structure is composed of sechser silicate layers with 4-, 8-, and 16-membered rings. The largest 16-membered rings have an average dimension of ∼8.93 × 9.42 Å2. β-K2(UO2)Si4O10 has been obtained by the high-temperature flux growth method. Its 3D framework contains a loop-branched sechser single layer with 4- and 8-membered rings and consists of the same [USi6] heptamers as observed in K4(UO2)2Si8O20·4H2O. Na6(UO2)3(Si2O7)2 has also been synthesized from melted fluxes and represents a 2D layer structure composed by [USi4] pentamers. Two iso-structural compounds A + (UO2)(HGeO4)·H2O ( A + = Rb+, Cs+) were synthesized via the hydrothermal method, and their structures are of the α-uranophane type. The 2D layers consist of [U2Ge2] tetramer secondary building units (SBUs). The Raman spectra of all novel phases were collected, and bands were assigned according to the existing oxo-silicate rings and oxo-germanium units. Additionally, we performed a statistical investigation of the local coordination of uranyl ions in all known inorganic structures with different oxo-anions ( TO x , T = B3+, Si/Ge4+, P/As5+, S/Se/Te6+, Cr/Mo/W6+, P/As3+, and Se/Te4+). We found a direct correlation between the ionic potential of the central cations T in oxo-anions in their higher oxidation states and the coordination number of uranyl groups.

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“…35 The ratio of uranyl to molybdate is 1:2, resulting in flexibility of this sheet to yield numerous structures. 35,36 Additionally, two previously reported compounds with this sheet topology also contain hydronium in the interstitial space, (H 3 O)[(UO 2 )(SeO 4 )(SeO 2 OH)] 37 and 38 The structure of 4 is the first reported structure of this sheet topology containing sulfate.…”

Section: T H Imentioning

confidence: 90%

Actinide Sulfate Structures from Caustic Solvents

Sweet,

Sockwell,

Hixon

et al. 2024

Inorg. Chem.

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Four unique actinide sulfates were synthesized using solvothermal techniques with strong acids. The first plutonium(III) sulfate structure, Pu(HSO 4 ) 3 , was synthesized and is isostructural with analogous lanthanide-based frameworks. A similar synthesis approach yielded crystals of NpNa 0.5 (HSO 4 ) 15 (SO 4 ) 1.5 , which has a comparable framework to the Pu(III) compound, but the neptunium metal is tetravalent and sodium is incorporated into the structure, as confirmed by chemical analysis. Anhydrous neptunium sulfate, Np(SO 4 ) 2 , is reported and is isotypic with U(SO 4 ) 2 . Finally, (H 3 O) 2 (UO 2 )-(SO 4 ) 2 , which contains a uranyl sulfate sheet structure, was synthesized and characterized. The corresponding sheet anion topology has previously been reported with various oxyanions, but this is the first report that contains sulfate. The sheets are charge balanced by hydronium cations in the interstitial space. This compound readily degrades and forms crystals of the synthetic analogue to the uranium mineral shumwayite, which is likely thermodynamically favorable. All four of these actinide sulfate compounds were synthesized in extremely acidic media, resulting in interesting and unique structures.

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Crystal chemistry of selenates with mineral-like structures: VII. The structure of (H3O)[(UO2)(SeO4)(SeO2OH)] and some structural features of selenite-selenates

Cited by 6 publications

References 6 publications

Crystal Chemistry and Structural Complexity of Natural and Synthetic Uranyl Selenites

Crystal Chemistry and Structural Complexity of Natural and Synthetic Uranyl Selenites

Structural and Spectroscopic Investigation of Novel 2D and 3D Uranium Oxo-Silicates/Germanates and Some Statistical Aspects of Uranyl Coordination in Oxo-Salts

Actinide Sulfate Structures from Caustic Solvents

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